With regards to my previous questions/posts, I received the following reply from a CGC representative via email:
First appearance label notations are made at the discretion of the CGC Grading Team. You can find this information by visiting the CGC Census which will include the Key Comments, Art Comments, and First Appearance notations.
If you would like to request a first appearance update or inclusion to the current label, please include a note along with the book in your submission (post-it on comic bag).